"Christian McArdle" wrote in message
. net...
If a house needs a secondary loop it also needs a grown up heating
system
that will include a stored HW of some type (vented, unvented or thermal
store).

Having hot water in less than a second is a luxury rather than a
necessity. If it were easily possible with my new combi I would do it.
Since it seems not to be I shall be content with waiting 30 seconds!

Actually, there is some environmental benefit as well as a convenience
one,
due to the reduced wastage of water. I would suggest that a secondary loop
that has a boost button that you can press before have a bath, or before
sitting on the toilet (so it is ready when you finish) means that energy
is
actually saved as well as water. However, a secondary loop constantly on
connected to a combi is likely to be somewhat wasteful of energy.

Have a flow switch on the lines to the toilets. When a flush the pump comes
on. Or have an infra red sensor in the kitchen too. When occupied the pump
runs. People in the kitchen tend to use water. Still have pipe stat when
it reaches 40-45C.

Using a pipe stat in a well insuated loop would mean the pump would not
cycle too often anyhow.